Open field surveys to evaluate the susceptibility of red raspberry genotypesto raspberry gall midge, Lasioptera rubi Schrank (Diptera, Cecidomyiidae)

Abstract: Earlier investigations on raspberry gall midge, Lasioptera rubi Schrank (Diptera,Cecidomyiidae) in untreated raspberry plots focused on harmfulness, flight period and life-cycle.Further observations were conducted during 2008 and 2009.Raspberry cane samples were collected from five raspberry genotypes (Willamette,Tullameen, Latham, Meeker and the hybrid K 81-6) in an abandoned raspberry plot in Zdravljak.Collected canes were brought to the laboratory where the diameter of canes was measured, anddiameter, length and width of galls and number of larvae in galls were recorded.During 2008 and 2009 growing periods, we registered different number of infested canes,galls/canes, larvae/gall on the genotypes.No galls have been observed in Meeker in 2008 and in Latham and Tullameen in 2009.During both research years, galls were found on primocanes at a height not exceeding 70 cm andsporadically observed on fruiting canes and petioles. The most vigorous canes were observed inhybrid K 81-6.Galls were the bigger in Tulameen in 2008. The highest number of larvae per cabin wasregistered in Tullameen in 2008 and K81-6 in 2009 (40 and 43, respectively). The presence ofeggs was registered in Tullameen, Willamette and hybrid K 81-6. The highest larval pressure wasfound in Latham (24.5 larvae per gall) and the smallest in Willamette (4.5 larvae per gall).